Orthoester stabilized polyvinyl-chloride resins



United States Patent Oflice 3,525,710 Patented Aug. 25, 1970 Int. Cl. C0815 45/58 US. Cl. 260-4595 5 Claims ABSTRACT OF THE DISCLOSURE Polyvinyl chloride resins are thermally stabilized by the addition of an orthoester having the formula polyhydric alcohol in a concentration of from 1% to The present application is a division of my application 612,066, filed Dec. 12, 1966 now abandoned, which in turn is a continuation-in-part of my earlier filed applications, Ser. No. 403,353, filed Oct. 12, 1964 now abandoned and 499,093, filed Oct. 20, 1965 now abandoned.

The present invention relates to the stabilization of resins, and more specifically to a novel stabilization agent for stabilizing vinyl chloride polymers and copolymers against the degradation effects of elevated temperatures.

It is well known that vinyl chloride containing resins degrade at elevated temperatures. When vinyl chloride polymers and copolymers are subjected to molding temperatures in excess ofabout 150 C. they tend to discolor. Serious discoloration occurs even in the relatively short period of time required for a molding operation.

To date, numerous stabilizers have been suggested for use in vinyl chloride type resins. The most satisfactory of these stabilizers comprise tin, lead and cadium containing compounds. These compounds, while performing satisfactorily where toxicity is not a problem, can not be used where the treated polymer is to come into contact with foodstuffs and the like.

As of present, a highly effective polyvinyl chloride stabilizer which does not possess toxic characteristics or propensities has not been developed.

It is therefore an object of the present invention to provide a novel class of polyvinyl chloride stabilizers.

It is another object to provide novel stabilizers for polyvinyl chloride containing resins which substantially enhance thermal stability of said resins.

It is a further object to provide a class of polyvinyl chloride stabilizers which are non-toxic and may be used in resins which are used in the packaging of foodstuffs materials.

These and still further objects of the present invention will become readily apparent to one skilled in the art from the following detailed description and specific examples.

Broadly, my present invention contemplates as polyvinyl chloride stabilizers compounds containing the following ortho ester grouping:

J) 45-0-1- I l wherein the indicated unsatisfied valences are occupied by hydrogen or organic radicals. It is also contemplated that these orthoesters may be elfectively combined with polyhydric alcohols to give a superior degree of stabilization.

More specifically, I have found that if from about 1% to about 10% by weight of a compound containing an ortho ester grouping is admixed with polyvinyl chloride, the ortho ester compound will stabilize the polyvinyl chloride towards heat induced degradation. Furthermore, this stabilization effect may be enhanced by the addition of polyhydric alcohols.

The ortho esters used in the practice of the present invention may be broadly defined as those ortho esters which possess at least one of the above defined ortho ester groups, and which are compatible with the polyvinyl chloride resins at the processing temperatures indicated. By the term compatible it is meant that the ortho ester used should homogenously blend withthe polyvinyl chloride and should have a relatively low vapor pressure at processing temperatures so as not to cause excessive foaming of the resins at the processing temperature encountered.

Typical structures of suitable ortho esters which may be used in the practice of my invention are:

kenyl; R R and R may be alkyl, phenyl, phenyl-alkyl, alkylphenyl, and al'kylphenyl-alkyl.

wherein R R and R, has the meaning given in 1) above; R may be alkylene, phenylene, and alkylphenylene; and X represents oxygen, and sulfur.

(3) R1 Rt 0 0 Rani... a. 1 n I I 3 wherein R, R and R have the meaning given above (1) R may be alkylene, phenylene, alkylalkylene, alkenylene, alkenyl-al'koxy-alkylalkylene and alkynylene; and n has a value of from 1 to 4.

R |-o 0 R1 wherein R and R have the meaning given in (1) above; and R may be alkylene, alkylalkylene, and alkenylalkoxylalkylene.

wherein R has the meaning given above and R, is alkylene.

The reaction products of lower orthoesters such as triethyl orthoacetate and triethylorthoformate with polyols such as glycerol, sorbitol, and mannitol yield complex esterified products.

Specific examples of orthoesters which may be used in the present invention along with a general description of how the orthoester compound may be prepared are given in the following paragraphs. (The numeral designations will be used in the subsequent specific examples and claims to identify these compounds.)

The following three methods may be used to prepare the following orthoesters:

(A) Iminoester route, as set forth in Pinner, Ben, 16 35 6, 1644 (1883).

The appropriate nitriles are reacted with one equivalent of dry hydrogen chloride and one equivalent of alcohol to form an iminoester hydrochloride which is then alcoholyzed with an excess of alcohol to form the orthoester. The reaction may be outlined as follows:

BX GGS S (B) Exchange reaction as described by Mkhitaryan, V. J. Gen. Chem. (USSR) 8 1361 (193 8).

The alkoxy groups of a readily available orthoester such as triethyl orthoacetate or formate are displaced by a higher boiling alcohol or polyol as follows:

Furthermore, the reaction may be carried out in two steps with two different alcohols or polyols i c g polyols ranging from diols to hexols. Typically the reaction may be illustrated for a diol as follows:

When more complex polyols including triols through hexols are used, many complex polymeric products are possible. However, these reaction products are formed by continuing the reaction until the required amounts of lower alcohol has been removed. That is the exchange reaction is continued until the calculated amount of lower alcohol is displaced by the higher alcohols.

(C) Alcoholysis of triholomethyl groups as set forth by Sah, P. and Ma, S.T., J. Am. Che., Soc. 54 2964 (1932).

The appropriately substituted trichloromethyl compound is treated with a metal alkoxide.

(I) 002115 CH3 OCzH5 CHs- -O- HCH2OACH3 66235 002115 This compound is conveniently prepared by routes A or D.

11) 002115 OOzHs CHa( JO -CH2O( 3CHs 0C2H5 j; 0C2H5 This compound is prepared by routes A or B.

02H: z a t) t) CHa-O-CHz-CECCH2-O-OH3 5 t) (5211 ([1211; T his compound is prepared by routes A or B.

(IV) OH: OH:

CHa-Cfi CH2 CHs-Cfi CH2 0 (I) CH3 0 O CHa COHGH2OHzO CCHs This compound is prepared by routes A or B.

(V) CH2-CH2 CH2CH2 O O O O GHQ-COCH2CH2O-CH2CH2O CCHs This compound is prepared by routes A or B.

W 033-011-0112 CHzCHs o 0 CH3 0 CH3 -OOJJH3CH2O CCH3 This compound is prepared by routes A or D.

(VII) OCHz CHsC- OCHzCCHz-CH3 O-OH2 This compound is prepared by route A.

(VIII) GHzOCH2CH=OHz CHa-C-OCH2 H CH20CCHB Hzl (3H2 Hid $112 \C/ HsC2CCH2OCH2CH=CH3 024R CHzO CH2CH=CH8 This compound is prepared by route B.

(XI) CH3 CH3 CH3 CH3 (13 cllm 0 CH2 0 0 CH3 0 0 CH3 OOCHFAJCHZO CCCHB This compound is prepared by routes A and B.

wherein n has a value greater than 1.

This compound is prepared by route B.

(XII) This compound is prepared by route A.

(XIII) (CH O) C-CH CH SCH CH C(OCH This compound is prepared by route A.

This compound is prepared by route A.

(CH O CCH CH OCH CH C (OCH 3 ,This compound is prepared by route A.

(XVI) s( s)1n 3)a This compound is prepared by route A.

(XVII C(O CH3):

' compound is prepared by route (X-VIII) I CH3C(-OCH2(CH2)6CHZ)2 OOHa This compound is prepared by route A.

This compound is prepared by route A.

This compound is prepared by route A.

CH2OCH2CH=CH2 This compound is prepared by route B.

6 This compound is prepared by route B. (XXIII) I CZHE A H--O 02115 O C2H5 This compound may be prepared by routes A, B, or C.

(XXIV) CH3 CH3 CH3 CH3 0 0 on; \CHZ 0E2 om A A (i 5 CHa COOII2CHzO OOHa This compound may be prepared by route B.

ws This compound was prepared by route B.

(XXVI) CHaC(OCH2@)a This compound was prepared by route B.

(XXVII) Poly glyceryl orthoformate) This compound was prepared by way of route B using one mole of triethyl orthoacetate and one mole of glycerol (XXVIII) Poly (sorbityl orthoacetate) This compound was prepared by route B from 2 moles of triethyl orthoacetate and one mole of sorbitol.

(XXIX) Poly(mannityl orthoacetate) This compound was prepared by route B using 2 moles of triethyl orthoacetate and one mole of mannitol.

The effectiveness of the present orthoester stabilizers may be enhanced by adding thereto from about 0.1 to about 10 moles of a high boiling alcohol per mole of orthoester.

Typical alcohols which may be added possess the general structure wherein R is an organic radical and x has a value of from 1 to 6. Preferably these alcohols have a boiling point in excess of about C.

In the above formula-R may be alkyl, alkylphenyl, phenylalkyl, alkylene, phenylene, polyalkoxyalkylene and trivalent counterparts thereof. Typical polyhydric alcohols useful in the practice of the present invention are a, m,

' -xylen'e, a, a-diOl, trimethylolphopane monopropyl ether,

trimethylolpropane monallyl ether, propylene glycol, diethylene glycol, dimethyloctadiynediol, pentaerythritol trimethylolpropane, neopentylglycol, benzylalcohol, cetyl alcohol and dipentaerythritol.

Polyvinyl chlorides which are treated in accordance with the practice of my present invention are those vinyl chlorides polymers and vinyl chloride copolymers having a number average molecular weight from about 10,000 to about 150,000 and a weight average molecular weight of from about 20,000 to 1,000,000. These vinyl chloride polymers and copolymers are well known to those skilled in the art and compromise vinyl chloride homopolymers as well as vinyl chloride copolymers which are prepared by copolymerizing vinyl chloride with a copolymerizable monomer such as unsaturated esters which include vinyl acetate, vinyl formate, vinyl benzoate, vinyl stearate, vinyl oleate, as well as diethyl maleate and diethyl formate. Copolymers may also be prepared by copolymerizing vinyl chloride with an acrylic ester such as methyl'-, ethyl-, butyland octyl acrylate. It is also contemplated 7 that the vinyl chloride copolymers may be prepared by polymerizing vinyl chloride with vinylidene chloride. The above mentioned copolymers may contain from to 20, and even 40% by weight of copolymerizable monomer.

The stabilization agents, namely the ortho esters contemplated herein, are incorporated with the vinyl chloride polymer and copolymers by any conventional means. The blending may be conveniently carried out first preparing a slurry of finely divided polymer in a solvent for the ortho ester such as methanol, acetone, ethyl ether. The solution is then separated from the slurry and the polymer particles are dried. This results in polymer particles which are thoroughly coated with the ortho ester set forth herein. It is also contemplated that the blending may be achieved by milling the polymer at the softening temperatures therefor until an intimate blend of the stabilization agent with the polymer is achieved. Milling is generally conducted at conventional temperatures of 150 to 200 C. for a period of time sufiicient to obtain thorough blending of the stabilization agent with the polymer.

The stabilized vinyl chloride polymers and copolymers contemplated herein may be used in the formation of rigid polyvinyl chloride molded articles. These rigid molded pieces are formed in extrusion and injection molding devices which are well known to those skilled in the art and which operate in the neighborhood of 0 to 200 C. The stabilization agents contemplated herein effectively stablize the vinyl chloride polymer and copolymer during the molding process and make it possible to produce rigid moldings having a low degree of color change and good clarity.

It is also contemplated that the polyvinyl chloride resins stabilized by the present stabilizers may be admixed with various plasticizers such as high boiling esters including the alkyl phthalates, phosphates, adipates, sebacates, azelates, and various polymeric type ester plasticizers. Also the present composition may contain other additives such as Zn, Mg, Sn and Ca salts of carboxylic acids, and phosphate esters. Furthermore, the resins may be included in plastisol type preparations which are fabricated by dipping and deposit type molding techniques.

Having described the basic aspects of my present invention the following specific examples are given to illustrate embodiments thereof.

EXAMPLE I In the examples tabulated below 9.5 g. portions of pow dered Vygen 120, high molecular weight polyvinyl chloride resin, was slurried in solutions which comprised ml.

of methanol and 0.5 g. of the various stabilizer compounds listed below. The resultant slurries were evaporated to dryness with constant agitation at from 40 to C. and under 60 mm. Hg pressure. 3.5 g. of the polyvinyl chloride mixtures were then pressed into plaques which measured 1 x 3" and 5 mils in thickness on a press heated to 200 C. and exerting 10,000 p.s.i. for the times listed in the table below. The color of the resultant plaques were measured by comparison with the standard Gardner color scale (0.0 colorless to 5.0=dark amber). The less color developed in the plaque the more effective is the stabilizer.

Gardner color index at various time, minutes Stabilizer 2 5 10 15 XIV 2.0 2.25 2.5 2.5 XVII 3. 0 3. 0 3- 0 3. 0

. Dibutyl tin dilaurate..- 7 11 15 15 None 15 15 15 15 Example 1 and 2 containing the ortho esters contemplated herein are effectively stabilized. Example 3 which contained the well known stabilizer dibutylin dilaurate rapidly discolored under the same conditions as did EX- ample 4 which contained no stabilizer.

EXAMPLE II In the following runs particulate polyvinyl chloride having a number average molecular weight of about 38,000 was dry blended with various amounts of orthoester and/ or polyhydric alcohol. These samples were then placed in the mixing chamber of a Brabender Plastegraph at C. and open to the air. A roller speed of 60 rpm. was used to knead the polymer formulations. The Brabender Plastograph continuously records the torque required to knead the mass. From the torque values one can determine;

(a) The time required for the powder mixture to fuse into a workable plastic mass (flux time).

(b) The force required to work the plastic mass (average torque value).

(c) The onset of crosslinking (decomposition time). The actual temperature of the plastic mass was also continuously measured. Small samples of the polymers were also removed periodically from the mixing chamber and their color compared to those of the standard Gardner scale.

TABLE Ir Decom- Ooncenposition trations, time Color (Gardner Scale 0=Colorless,

parts per Flux after 15=Brown) Stabilizer (numerals refer orthoester described prehundred time, flux, Torque, Polymer, Run v10us1y) mm. min. Kg. temp. min2 e 11111110 miifi 11111210 1 v 5.0 2.0 20.0 1.25 199-204 1.5 1.8 1.5 1.5 1.5 --3 1.5 20.0 1.25 193-199 0.2 0.2 0.5 1.0 1.2 3 ggm g rag 4 g g: 1.5 22.0 1.1 190-198 1.5 1.5 1.5 1.5 11.5 5 m-Xylene 13.241101" 2.0 3.5 10-135 1. 9-1.5 190-210 1.5 6

92 111-; are .9 7 oyenea,ai0 s v 5.0 9 gglnlgihylol propane monoallyl ether (TMPA g} 3-3 a g; 510 210 14:5 113-114 190-203 1.5 g: 3 2. 0 12. 5 1. 4 190-200 1. 0

13 methylene glycol g 2.5 17. 0 1.8 2. 0 190-202 1. 0 5'" (gxidlzed polyethylene (011112'555111) 1 '1: n V: 2 0 27 1 1 190-198 1 5 16 Trlmethylol/propane dlallyl ether; g gi thyloetadiynediol (DMOD) i 3 1 1 gigg} 2.5 15.5 1.1-1.4 199-190 1.0 19 v1- 5. 0 2. 0 7. 5 1. 4 190-198 1. 0

Decom- Coneenposition trations, time Color (Gardner Scale =Colo119ss, parts per Flux after 15=Brown Stabilizer (numerals refer orthoester described prehundred time, flux, Torque, Polymer, Run viously) min. min. Kg. temp. 2 4 mm. min. min. mm. mm:

5. 0 9.0 8 5 1 4 -192 1.0 5. 0 2. 0 12 0 1. 4-1. 6 190-214 1. 5 5.0 2.0 8 5 1.4 139-196 1.0 5. 0 1. 0 8. 5 1. 2-1. 8 180-197 2. 2 5. g 1. 0 12-21 1. 6-1. 8 181-210 2. 2 5. :3} 1.0 22.0 1.3 1.8 178 200 0. 5. CHBCHPO'(CHZOH)Z 1.0 25.5 1.1-1.8 180-200 0.7

OH OCH CH CH 2 z r a 1.0 12 1.1-1.8 180-200 2.3

2.0 1 9 1.2-1.4 182-197 2. 0 3.0 2. 0 17 1. 1-1. a -198 2. 0 3. 0 2. 0 10 1. 2-1. 4 178-202 2. 5 3. 0 .2. 0 7. 5 1.2-1.4 186-196 2. 0 2. 5 2. 0 3. 0 1. 2-1. 4 188-192 2. 5 2. 8 a. 0 4 5 1.85 20 -212 8 15 a. 0 9. 0 1. 8 190-208 2. 5 9. 0 a. 0 9. 5 1. 9-1. 4 184-198 5. 0 6.0 2. 0 14 0 1. 3-1. 4 190-203 1. 8 1. 8 8. 0 9. 0 1. 1-1. 4 194-209 1. 8 1. 8 2. 5 6. 5 1. 4 198-201 1. 8 1. 8 2. 5 4 5 1. 3-1. 4 194-200 2. 5 9. 0 4. 0 2. 0 1. 3-1. 5 180-188 1. 0 2. 0 2.0 15.5 1. 8-1.4 190-206 0.5 0.5 2. 5 11.0 1. 8-1.4 190-200 0.5 1.0 9.5 4.5 1.1-1.5 186-198 0 2. 0 I 16 1. 1-1. s 190-199 1. 5 2.0 19 1.1-1.4 188-200 1.0

0 5 5-6 0 1. 75-2. 1 174-192 7 0 0 5. 5-7 5 1.6-1. 9 193-208 5 0 0 9-10 2. 0-2. 4 194-200 2 0 X X 0 9-10 1.8-2.1 180-218 10 Cetyl alcohol. 0 14 1.8-2. 4 190-212 2 0 Stearic acid. 68 XXX Cetyl 51661161 0 5 5 1 8-2 4 192-206 2 0 Stearic acid XII Cetyl alcohol. 0 15. 5 1.4-2.4 190-210 2.0 2.0 2.0 9.0 Stearic acid- 70 XXVIII.--

08m fllcOhOL 0 7. 5 1.7-2.4 190-214 7. 5 7.5 Stearic 0cid g g jgf g o 5. 5 1.9-2.1 192-210 15 1 1.5 after 25 min.

1 Blk after 23.5 min. 3 Black.

4 2.0 at 30 min.

5 2.0 at 25 min.

1.5 after 25 min.

7 3.0 after 25 min., 3.5 after 30 min. 9 After flux.

9 Ill=deiine.

Blk at 7.4 min:

B Black 11 12 Iclaim: 3. The composition of claim 1 wherein said ortho- 1. A thermally stabilized polyvinyl chloride resin comester has the formula: position comprising vinyl chloride and a compound of (CH O) CCH CH SCH CH -C(OH the formula: 4. The composition of claim 1 wherein said orthoester .M. A, v. i .r, It gi. n

(C H O CCH CH SCH CH -C (OC H 3 0 v I 5. The composition of claim 1 wherein said orthoester l "0R9: has the formula:

g CH O CCH CH OCH CH C (OCH 3 wherein R R and R are selected from the group convReta-cums C'ted sisting of alkyl, phenyl, phenylalkyl, alkylphenyl and UNITED STATES PATENTS alkylphenylalkyl; R is selected from the group consisting 2,789,101 4/1957 Wilson 2604585 XR of alkylene, phenylene and alkylphenylene; and X is selected from the group consisting of oxygen and sulfur. 15 DONALD ECZAJA, P i E i 2. The composition of claim 1 which contains from M I WELSH A E about 1 to about 10% by weight of an alcohol having a sslstant Xammer boiling point in excess of about 175 C. and having the U S Cl X R formula R(OH) wherein R is an organic radical and x has a value of from 1 to 6. 260-23, 4 45-85 

